Instrument and method for implanting an interbody fusion device

ABSTRACT

A holder is provided which couples to the spine. In an embodiment, the holder has two conduits into which sleeves may be inserted during a spinal fusion procedure. The holder may have a distractor extending from the bottom of the holder. The distractor secures the holder to the spine and maintains a proper separation distance between adjacent vertebrae. The sides of the distractor may be serrated to better secure the holder to the spine. The sleeves and conduits serve as alignment guides for instruments and implants used during the procedure. In an embodiment, the holder may include holes for fasteners that fixably secure the holder to vertebrae adjacent to a disk space. A flange may be placed around the holder to shield surrounding tissue and to provide a placement location for adjacent blood vessels during the spinal fusion procedure.

This is a continuation of copending application Ser. No. 09/478,923filed Jan. 6, 2000.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to spinal fixation and fusionsystems. The invention also generally relates to an insertion guide usedduring the insertion of a spinal implant system, wherein the implantsystem is used for correction, fixation, and/or stabilization of thespine.

2. Description of the Related Art

Intervertebral disks that become degenerated due to various factors suchas trauma or aging typically have to be partially or fully removed.Removal of an intervertebral disk can destabilize the spine, making itnecessary to replace the vertebral disk to maintain the height of thespine and to fuse the spine. Spinal implants are often used to preventcollapse of the spine. In a typical spinal fusion procedure, anintervertebral disk is removed and implants are inserted in the diskspace between neighboring vertebrae. The implants maintain normal diskspacing and help restore spinal stability.

The implants may be constructed of any biocompatible materialssufficiently strong to maintain spinal distraction including, but notlimited to, bone, stainless steel, or inert metals. Implants aretypically packed with bone graft or a synthetic bone graft substitute tofacilitate spinal fusion. Implants may have a variety of shapes, whichinclude, but are not limited to, threaded cylinders, unthreadedcylinders, and parallelepipeds.

An anterior spinal fusion procedure is often preferred to a posteriorspinal fusion procedure. An anterior spinal fusion procedure may requireless bone removal and muscle distraction than a posterior spinal fusionprocedure. Also, an anterior spinal fusion procedure may involve lessrisk of nerve damage than a posterior spinal fusion procedure. In ananterior spinal fusion procedure, a surgical opening in the abdomen maybe up to ten inches deep. A protective sleeve may be used duringpreparation and insertion of a spinal implant. The protective sleeve mayserve to protect abdominal organs, blood vessels and other tissue duringthe spinal implant procedure. The sleeve typically extends above thesurgical opening during use. The sleeve may maintain distraction of thevertebrae. Also, the sleeve may serve as an alignment guide for tool andimplant insertion during the surgical procedure.

Protective sleeves typically have distractors on a distal end.Distractors are projections that may be inserted into a disk spaceduring a spinal fusion procedure. The distractors may serve to achieveand maintain distraction of adjacent vertebrae. Distractors may alsohelp to secure the protective sleeve to the spinal column during theprocedure. Protective sleeves may have one tube or two parallel tubes.FIG. 1 shows a single-tube protective sleeve, and FIG. 2 shows adual-tube protective sleeve.

FIG. 1 illustrates a single-tube protective sleeve 30 used in a spinalfusion procedure. A spinal fusion procedure involves the insertion ofone or more implants in a disk space between two vertebrae. Protectivesleeve 30 includes a substantially long, hollow tube 32, two distractors34 on opposite sides of an end of the tube, and two spikes 36 (only oneshown) on opposite sides of the end of the tube. Protective sleeve 30 istypically sufficiently long to allow access to a spinal column of alarge patient during an anterior procedure. Protective sleeve 30 mayalso be used in a posterior spinal fusion procedure.

A spinal fusion procedure using implants typically involves theinsertion of two implants that are bilaterally positioned in anintervertebral disk space. During an anterior procedure, the disk spaceis prepared by performing a discectomy and by distracting the vertebraeadjacent the disk space. A cap (not shown) is placed on end 38 of theprotective sleeve 30 opposite distractors 34 to protect the end of thesleeve during insertion. Distractors 34 may then be hammered into thedisk space by striking the cap with a mallet (not shown). Spikes 36 arehammered into disk bone on the vertebrae and help to stabilizeprotective sleeve 30 during the procedure. Distractors 34 serve toseparate the adjoining vertebrae to approximately normal spacing.

After insertion, a hole is drilled in the disk space by inserting a toolwith a reaming head attachment through tube 32 and rotating the tooluntil a predetermined depth is reached. In some procedures, the hole isthen tapped by inserting a tool with tap head attachment through tube 32and rotating the tool until a predetermined depth is reached. The topand bottom of the reamed and tapped hole may extend into the end platesof the adjacent vertebrae. After the hole is prepared, an implant may beinserted in the hole by attaching the implant to an implant insertiontool and inserting the implant through tube 32. For untapped holes, theimplant may be hammered into the hole by striking the implant insertiontool with a mallet. For tapped holes, the implant may be threaded intothe hole by turning the implant insertion tool. Then, the protectivesleeve 30 may be removed.

If a second implant is to be inserted, the protective sleeve 30 ishammered in the disk space opposite the first implant and the procedureis repeated. Alternatively, the protective sleeve 30 may remain insertedin the disk space, and a second single-tube protective sleeve 30 may beinserted adjacent to the protective sleeve.

The optimal alignment and spacing of implants in a spinal fusionprocedure may be determined before surgery. Achieving the predeterminedalignment and spacing during surgery is often important for optimalfusing of the adjacent vertebrae. Protective sleeve 30 hascharacteristics that may make achieving alignment difficult. First, eachof the two holes is aligned, reamed, and tapped in a separate procedure.It is often difficult to align and space the holes correctly. Second,the alignment of protective sleeve 30 must be maintained afterinsertion. Any slight movement of protective sleeve 30, which may actlike a lever arm, may result in misalignment of the hole.

FIG. 2 illustrates a dual-tube protective sleeve 40 used in a spinalfusion procedure involving the insertion of two implants into a diskspace. Protective sleeve 40 includes substantially long, hollow tubes32, one or more distractors 34 and one or more spikes 36. Protectivesleeve 40 is typically long enough to allow access during an anteriorprocedure to an intervertebral disk in a large patient. Spinal fusionusing implants with protective sleeve 40 involves the insertion of twoimplants, bilaterally positioned in parallel in an intervertebral diskspace. During an anterior procedure, the disk space is prepared byperforming a discectomy and by distracting the vertebrae adjacent thedisk space. A cap (not shown) is placed on the end 42 of protectivesleeve 40 opposite distractor 34 to protect the sleeve during insertion.Distractor 34 is then hammered into the disk space by striking the capwith a mallet (not shown). Spikes 36 are hammered into disk bone on theadjacent vertebrae to help stabilize protective sleeve 40 during theprocedure. Distractor 34 serves to separate the adjoining vertebrae toapproximately normal spacing. After insertion, holes are reamed in thedisk space by inserting a tool with a reaming head attachment throughtubes 32 and rotating the tool until a predetermined depth is reached.In some procedures, the holes are tapped by inserting a tool with a taphead attachment through tubes 32 and rotating the tool until apredetermined depth is reached. The top and bottom of the reamed andtapped holes may extend into the end caps of the adjacent vertebrae.After the holes are prepared, implants are inserted in the holes byattaching the implants to an implant insertion tool and inserting theimplants through tubes 32. For untapped holes, the implants are hammeredinto the hole by striking the implant insertion tool with a mallet. Fortapped holes, the implants are threaded into the holes by turning theimplant insertion tool. After both implants are inserted, protectivesleeve 40 is removed.

FIG. 3 shows a representation of implants inserted into disk space 44using a dual-tube protective sleeve 40. Spinal nerves in the spinalcanal 46 are protected by dura 48. Nerves 50 extend from the spinalcanal 46. Implants 52 are inserted between two vertebrae 54 (one shown).Care must be taken during insertion of the implants 52 to make sure thatthe implants do not impinge on the nerves 50.

Like single-tube protective sleeve 30, dual-tube protective sleeve 40has characteristics that make it difficult to align the implantscorrectly. First, the alignment of protective sleeve 40 must bemaintained after insertion. Any slight movement of sleeve 40, which mayact like a lever arm, may result in misalignment of the hole. Second,the long parallel tubes make it difficult to angulate the two implants52 relative to each other. Angulated implants may be the desiredalignment in some spinal fusion procedures. Using a dual-tube protectivesleeve 40 has the advantage that the surgical procedure is simplifiedbecause there is only one insertion procedure, as opposed to twoinsertion procedures for a single-tube protective sleeve 30.

Single- and dual-tube protective sleeves share some disadvantages.First, the sleeves are typically unitary members that are long enough toextend out of a ten-inch deep surgical opening after being hammered intoplace. To maintain alignment after insertion, the sleeve must be kept asmotionless as possible. The sleeve tends to act like a lever arm, andany slight motion of the sleeve during the procedure may result inmisalignment of the implants. The sleeve acting as a lever arm isparticularly problematic when the sleeve is handed off during thesurgical procedure from one member of the surgical team to anothermember of the surgical team.

A second disadvantage of protective sleeves is related to the firstdisadvantage. The sleeve is held in place only by the distractors andthe spikes inserted in the disk space. This connection may not be verysecure. Because the connection is not secure, the sleeve may have to beheld by the members of the surgical team throughout the entire procedureto maintain proper alignment. As noted above, any slight movement canresult in the misalignment of the implants.

A third disadvantage of protective sleeves is that they may affordminimal protection to surrounding tissues during a spinal fusionprocedure. Major blood vessels, parallel the anterior surface of thespine for much of the spine's lower length. These vessels may beretracted during the procedure. The interface between the distal end ofthe sleeve and the spinal column is typically not a perfect fit. Gapsmay exist between the sleeve and the vertebrae. The presence of gapscreates the risk of drill bits, taps, and implants coming into contactwith the blood vessels or other surrounding tissues during theprocedure. Also, the blood vessels may be pinched between the sleeve andthe vertebrae. A nick or cut to either the aorta or the blood vesselscan be life threatening.

The above-mentioned methods and systems inadequately address the need toangulate implants in some spinal fusion procedures, the need to maintainprecise alignment throughout the procedure, and the need to protectsurrounding tissues during the procedure. It is therefore desirable thatan improved method and system be derived for inserting spinal implantsduring a spinal fusion procedure.

SUMMARY OF THE INVENTION

A holder or base may allow for the insertion of instruments and spinalimplants into a disk space during a spinal fusion procedure. In anembodiment, distractors and tangs of a holder may be driven into anintervertebral disc space. The distractors and tangs may secure theholder to the spine during use. In an embodiment, fasteners extendingthrough a holder into the adjacent vertebrae may be used to fix theholder to the spine. In another embodiment, distractors, tangs, andfasteners secure a holder to the spine. A flange may be placed aroundthe holder to protect the surrounding tissue and blood vessels.Protective sleeves may be inserted into and may be removed from conduitsin the holder. A portion of the sleeve may have a slot or a window,located adjacent to the top of the holder. The slot or window may serveas a view-port to provide increased visibility near the procedure site.Surgical instruments may be inserted through the protective sleeves andthrough the holder conduits to prepare the intervertebral space for animplant.

An embodiment of a holder includes a body, one or more conduits passingthrough the body from the top to the bottom, one or more distractors onthe bottom of the body, and one or more tangs on the bottom of the body.The body may have a smooth outer surface with no sharp corners. In someembodiments, the body may be flared near the bottom to provide shieldingfor surrounding tissue. The flared bottom may provide room for optionalfasteners to extend at oblique angles from the body of the holder. Theflared body may also provide the holder with a stable base against thespinal column.

An optional flange may be provided that fits around the outer surface ofthe holder. The flange may provide shielding of soft tissue, such asblood vessels and organs, from cutting tools at the junction of theholder and the vertebral bodies. The flange may also prevent damage tosoft tissues due to pinching of the soft tissue between the holder andthe vertebral bodies. The flange may be made of a rigid or semi-rigidmaterial. A portion of the flange may be made of an elastic material sothat the flange may stretch over and slide down the holder. In oneembodiment, the holder may include a rim for holding the flange in placeafter installation. In another embodiment, the holder may include agroove for holding the flange in place. In another embodiment, theflange has an elastic collar, which holds the flange in place againstthe holder.

In some embodiments, the inner surfaces of the conduits may containshoulders to limit the insertion distance of protective sleeves in theconduits. Above a shoulder, a conduit may be sized to match the outerdiameter of a protective sleeve. Below the shoulder, the conduit may besized to match the outer diameter of instrument heads and implants to beused in the procedure. In some embodiments, the shoulder may includeslots configured to engage distractors on protective sleeves; thusallowing the holder to be used with single-tube protective sleeveshaving distractors.

Embodiments of the holder may have non-circular conduits. The crosssectional shape of the holder conduits and the protective sleevesinserted into the holder may be any desired shape that allows for theinsertion of spinal implants into a disk space. For example, the crosssectional shape of the conduits may be rectangular if the crosssectional shape of the spinal implants are generally rectangular. Otherembodiments of the holder may have circular conduits or conduits whichdo not have a regular geometric shape. Embodiments of holders that havecircular conduits may be constructed with conduits of differentdiameters to accommodate protective sleeves and implants of differentdiameters.

Embodiments of holders may be provided with non-parallel angledconduits. Non parallel conduits allow the insertion of implants atoblique angles to improve spinal fusion and to protect nerves posteriorto the disk space. Other holder embodiments may have parallel conduits.

The distractors on the bottom of the holder body are projections thatinsert into a disk space during a spinal fusion procedure. Thedistractors may serve to achieve and/or maintain distraction of theadjacent vertebrae. The distractors may also secure the holder to thespinal column during the procedure. The distractors may be substantiallywedge-shaped, and may include curved surfaces. The tangs on the bottomof the holder body may serve to maintain distraction, and may alsomaintain a parallel orientation of the vertebrae during the procedure.The tangs may also be substantially wedge-shaped, and may also includecurved surfaces. Outer surfaces of the distractors and tangs may beserrated to secure the holder to adjacent vertebrae during a spinalfusion procedure.

In one embodiment, there is one distractor centrally located between twoconduits; and two tangs, with one next to each conduit opposite thedistractor. Curved inner surfaces on the tangs and curved surfaces onthe distractor may serve as partially enclosed extensions of theconduits, and may help maintain alignment of the implant during a spinalfusion procedure.

In some embodiments, the body includes one or more fastener holes forthe insertion of fasteners into vertebrae. The fastener holes may beangled so that fasteners inserted through the holes extend obliquelyinto adjacent vertebrae without damaging the vertebral endplates. Thefasteners may pass through the end caps of the vertebrae into cancellousbone in the interior of the vertebrae. The fasteners may serve tosubstantially anchor the holder to the spine during the spinal fusionprocedure.

The height of the holder, when inserted in a spine, may be substantiallyless than the length of a protective sleeve. During the spinal fusionprocedure, a protective sleeve may be inserted into a holder conduitwhen needed and removed when not needed without affecting alignment.Removal of a protective sleeve from the holder decreases the likelihoodof a protective sleeve being inadvertently used as a lever arm duringthe procedure. Removing a protective sleeve from the holder may increasevisibility at the procedure site. Removing a protective sleeve may alsoallow for easy irrigation of the entire surgical site, including theholes being prepared for the implants.

The ability to remove the protective sleeves when not in use, the shortprofile of the holder, and the fastener anchoring system all help tomaintain proper alignment during the insertion of implants in a spinalfusion procedure.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages of the present invention will become apparent tothose skilled in the art with the benefit of the following detaileddescription of embodiments and upon reference to the accompanyingdrawings in which:

FIG. 1 illustrates a single-tube protective sleeve;

FIG. 2 illustrates a dual-tube protective sleeve;

FIG. 3 is a representation of implants inserted into a disk space with adual-tube protective sleeve, or with an embodiment of a holder of thepresent invention that has parallel conduits;

FIG. 4 is a perspective view of a first embodiment of a holder;

FIG. 5 is a front view the first embodiment holder;

FIG. 6 is a side view the first embodiment holder;

FIG. 7 is a cross-sectional view of the first embodiment holder takensubstantially along line 7—7 of FIG. 6;

FIG. 8 is a cross-sectional view of the first embodiment holder takensubstantially along line 8—8 of FIG. 5;

FIG. 9 is a top view of the first embodiment holder;

FIG. 10 is a bottom view of the first embodiment holder;

FIG. 11 is a top view of an embodiment of a holder flange;

FIG. 12 is a top view of another embodiment of a holder flange;

FIG. 13 is a perspective view of an embodiment of a holder flange with acollar;

FIG. 14 is a perspective view of an embodiment of a holder flange;

FIG. 15 is a perspective view of an embodiment of a holder withoutconduit extenders;

FIG. 16 is a cross sectional view of an embodiment of a holder having aflange groove;

FIG. 17 is a cross sectional view of an embodiment of a holder withoutbody flare;

FIG. 18 is a cross sectional view of an embodiment of a holder with analternative fastener hole arrangement;

FIG. 19 is a perspective view of an embodiment of a holder havingserrated distractors and tangs;

FIG. 20 is a perspective view of an embodiment of a holder having anextended upper opening and an insertion tool slot.

FIG. 21 is a perspective view of the embodiment shown in FIG. 20;

FIG. 22 is a perspective view of an insertion tool for an embodiment ofa holder;

FIG. 23 is a perspective view of an alternate embodiment holder havingoverlapping conduits;

FIG. 24 is a top view of a possible arrangement of implants insertedinto a disk space using the holder of FIG. 23;

FIG. 25 is a perspective view of a holder having one conduit;

FIG. 26 is a perspective view of a holder with an inserted protectivesleeve and tool;

FIG. 27 is a front view of a holder with an alternate protective sleeve;

FIGS. 28a-28 e illustrate steps included in a spinal fusion procedureusing an embodiment of a holder;

FIG. 29 illustrates the positioning of major blood vessels around oneembodiment of a holder during a typical L5/S1 fusion procedure,

FIG. 30 illustrates the positioning of major blood vessels around oneembodiment of a holder during a typical L4/L5 fusion procedure; and

FIG. 31 illustrates the angulation of implants inserted using oneembodiment of a holder.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, a holder or base for use as an insertionguide during a spinal implantation procedure is designated generally as100. A holder may be used to support a sleeve during a spinal fusionprocedure, and a base may be used with or without a sleeve during aspinal fusion procedure. For illustrative purposes only, the followingdescription will describe a holder. A person having ordinary skill inthe art will understand that a holder may be used as a base, and a basemay be used as a holder.

FIGS. 4-10 show views of a first embodiment of the holder 100. Theholder 100 may include unitary body 102, conduits 104 through the body,conduit extenders 106, flared portion 108, flange rim 110, holes 112,distractor 114, and tangs 116. The height of the holder body may be lessthan about six inches. Preferably, the holder height is less than fourinches, and more preferably, less than 2 inches.

The conduits 104 may have circular cross sections. Alternatively, theconduits 104 may have any desired cross sectional shape, such asrectangular or ellipsoid, to correspond to instruments and implants usedduring a spinal fusion procedure.

As shown in FIG. 6, the body 102 may have flared portion 108. The flaredportion 108 may allow for angulation of fastener holes 112, as shown inFIG. 8. Fastener holes 112 may be located in slot 118. Angulatedfastener holes 112 allow fasteners 120 inserted through the fastenerholes to penetrate adjacent vertebrae 54 through end caps 122 of thevertebrae and into cancellous bone 124, as shown in FIG. 28c. Attachingthe holder 100 to the vertebrae 54 with fasteners 120 placed through endcaps 122 may minimize weakening of the end plates 126 of the vertebrae.Shoulders 128 limit the insertion depth of the fasteners 120 into theholder 100. Fasteners 120 may be any type of fastening device including,but not limited to, screws, nails, rivets, trocars, pins, and barbs.

The flared portion 108 of the body 102 may shield blood vessels, nerves,and other soft tissue from damage by the body and tools used during thespinal fusion procedure. In addition, the flared portion 108 increasesthe circumference of holder 100 to a maximum near flange rim 110.Optional flange 130 may slip over the top of holder 100 and resideagainst the rim 110. The flared portion 108 may also provide a stablebase on the end caps 122 of the vertebrae 54 for holder 100.

The perimeter of the conduit 104 at a top end of the holder 100 maymatch the outer perimeter of protective sleeve 132 inserted into theconduit. The conduits 104 may include shoulders 134. A shoulder 134prevents insertion of a protective sleeve 132 into a conduit 104 beyonda certain depth. As shown in FIG. 9 and in cross section in FIG. 7, aconduit 104 may include slots 136. The slots 136 correspond to the shapeof the distractors 34 on the ends of single-tube protective sleeves 30.Slots 136 allow a holder 100 to be used with a single-tube protectivesleeve 30 having distractors 34, such as the sleeve shown in FIG. 1. Inother embodiments, conduits 104 may be configured to receive protectivesleeves 132 without distractors 34 by having shoulders 128 which extendfully around the diameter of the conduits 104. A protective sleeve 132may be slid into a conduit 104 without the use of an insertion tool.

FIG. 7 shows a cross sectional view of the first embodiment holder 100with the conduits 104 angulated toward one another. Having the conduitsangled relative to one another allows for the angulation of implants 52.Angulated implants 52 may provide a more stable fusion of vertebrae 54.In addition, angulated implants 52 may be less likely to protrude fromposterior side 138 of the disk space to press on nerves 50 exiting thespinal canal 46. The angle A, located between a center line of a firstconduit 104 and a centerline of an adjacent conduit, may vary from 0 toabout 30 degrees, preferably the angle A is less than about 20 degrees,and more preferably, the angle A is less than about 10 degrees. If theangle A is 0 degrees, then the adjacent conduits 104 are parallel.

Flange rim 110 may support flange 130. The flange 130 may serve toprotect blood vessels and other tissue placed upon the flange 130 andnear the body 102 of the holder 100. FIGS. 11-14 show some flangeembodiments. In one embodiment, ends 140 of the flange 130 arerelatively wide to provide extra protection and a support area on thesides of the holder 100 where the blood vessels are most likely to beplaced. As shown in FIG. 14, the flange 130 may have flexible collar 142to more securely attach the flange to the body 102 of a holder 100. Theshape of the flange 130 during use may correspond to the anteriorsurface of the spine so that a snug fit against the spine is establishedduring a spinal fusion procedure. The snug fit may help prevent toolsused during the procedure from contacting and potentially damagingadjacent tissue. The flange 130 may be made of a semi-rigid elastic orplastic material so that an inner edge of the flange conforms to theshape of the holder body 102 after the flange has been stretched overand slid down the body. As shown in FIG. 14, the flange may have narrowbrims 144, and relatively short ends 140. The ends 140 of the flange 130are long enough to be easily positionable under adjacent vessels andtissue.

The distractors 114 and tangs 116 are protrusions, which may extend fromthe bottom of the holder body 102. Distractor 114 may serve to maintaindistraction of adjacent vertebrae 54 during a spinal fusion procedure.The distractor 114 may establish a separation distance between thevertebrae during the procedure. Tangs 116 may also serve to maintaindistraction. The tangs may maintain a parallel orientation of thevertebrae 54 during the procedure. Distractor 114 and tangs 116 may besubstantially wedge-shaped to facilitate insertion into the disk space44. Surfaces of distractor 114 and tangs 116 may be curved to match thecurvature of the conduits 104, so that the distractor and tangs serve aspartially enclosed extensions of conduits.

Bottom 146 of the holder 100, as seen in FIG. 5, may conform to thegeneral shape of a vertebra 54. When the holder is inserted into a diskspace 44, portions of the bottom 146 of the holder 100 may reside on endcaps 122 of adjacent vertebrae 54. Having the bottom 146 of the holder100 shaped to conform to the shape of the vertebrae 54 may help toprotect adjacent soft tissue and vessels from being pinched between theholder and the vertebrae during the spinal fusion procedure.

FIGS. 15-21 show some alternate embodiments of a holder 100. FIG. 15shows a holder without conduit extenders on the body 102. FIG. 16 showsa cross sectional view of a holder 100 with flange groove 148. Theflange groove 148 may support an inner edge of a flange 130 to hold theflange at a desired position on the body 102. FIGS. 16 and 17 show crosssectional views of holders 100 without fastener holes. FIG. 17 alsoshows the holder without a flared portion and without a flange rim or aflange groove.

FIG. 18 shows a cross sectional view of another embodiment holder withan alternate fastener hole 112 arrangement. In this embodiment, fastenerholes 112 extend between conduits 104 from the top of body 102 downwardsat an oblique angle relative to a vertical axis of holder 100. Thefastener holes 112 cross at point 150 and then exit near an outer edgeof the lower portion of body 102. The fastener holes 112 includeshoulders 128 to limit the insertion depth of fasteners 120 intofastener holes 112. To use this embodiment, one fastener 120 is insertedinto a fastener hole 112 and into a vertebra 54 until the head of thefastener is past the cross point 150. Then, another fastener 120 isinserted into the remaining fastener hole 112 and the fastener isinserted into the adjacent vertebra 54. Both fasteners 120 may befurther inserted into the vertebrae 54 until the fastener heads contactthe shoulders 128.

FIG. 19 shows an embodiment of a holder 100, which has serrations 154 onouter edges of the distractor 114 and on the outer edges of the tangs116. Serrations 154 may maintain proper alignment and the serrations mayinhibit the distractor 114 and tangs 116 from backing out of thevertebrae 54 after the holder 100 is inserted during a spinal fusionprocedure.

FIG. 20 and FIG. 21 show perspective views of an alternate embodiment ofa holder 100. The body 102 may include flat sections 156, large topopening 158, undercut tool slots 160, spring stop 162, and ball 164. Theflat sections 156 may help to make the holder 100 easier to machineduring the manufacturing. The holder may have large top opening 158 withconduits 104 located in a lower section of the body. The body 102 mayhave undercut tool slots 160 (only one shown). Coil springs (not shown)are placed in the body 102 between the spring stops 162 and the balls164 (only one shown). The spring stops 162, coil springs and balls 164form an assembly that removably connects an insertion tool 166 to theholder 100.

FIG. 22 shows a perspective view of the insertion tool 166 used with theholder shown in FIG. 20 and FIG. 21. The insertion tool 166 includesattachment head 168, dimples 170, shaft 172, and top member 174. Theattachment head 168 of the insertion tool 166 is inserted into the topopening 158 of the body 102. The insertion tool 166 is rotatedapproximately 90 degrees. Rotating the insertion tool 166 forces theballs 164 in the holder body 102 against the coil springs, andcompresses the springs. When the dimples 170 align with balls 164, thesprings force the balls into the dimples and attach the insertion tool166 to the holder 100. When the holder 100 is attached to the insertiontool 166, the insertion tool functions as a handle and allows the holderto be positioned at a desired location. A mallet (not shown) may be usedto strike upper surface 176 of the top member 174 to insert the holderinto a disk space 44 after the holder is positioned at a desiredlocation. To remove the insertion tool 166 from the holder 100, theinsertion tool is rotated approximately 90 degrees, and the attachmenthead 168 is removed from the opening 158.

FIG. 23 shows a perspective view of an embodiment of a holder 100wherein the conduits 104 of the holder overlap. The holder has a pair ofdistractors 114 located at opposite sides of the body 102. FIG. 24 showsa schematic representation of one possible arrangement of implants 52,53 inserted in a disk space 44 with the, embodiment of a holder 100shown in FIG. 23.

FIG. 25 shows an embodiment of the holder 100 having one conduit 104extending through the body 102. The holder 100 may have a pair ofdistractors 114 located at opposite sides of the conduit 104. The holdermay have fastener holes (not shown) that allow fasteners to attach theholder to vertebrae 54 during a spinal fusion procedure.

FIG. 26 illustrates an embodiment of a holder 100 with protective sleeve132, driver 180, and attachment 182. Tube 32 of protective sleeve 132may be inserted in one of the conduits 104 of holder 100. Shaft 184 ofdriver 180 may be inserted in tube 32. At least a portion of shaft 184may have a diameter substantially equal to the inside diameter of tube32 to maintain alignment of the driver 180 during use. Stop 186 mayserve to limit the distance shaft 184 may be inserted into tube 32. Insome embodiments, stop 186 may be adjustable to allow differentinsertion depths. The driver 180 may have handle 188 for turning shaft184 located on an end of the shaft. Attachment 182 may be located on anend of the shaft opposite to the handle 188. Attachments may include,but are not limited to, drilling heads and tapping heads. An implant 52may also be coupled to the distal end of a driver for insertion into adisc space 44.

FIG. 27 illustrates an embodiment of a protective sleeve 132 prior toinsertion into an embodiment of a holder 100. The protective sleeve 132includes widened portion 190 at an end of the sleeve. The widenedportion 190 receives a tool (not shown) having a complementary wideportion at an end of the tool. The sleeve 132 may include view-port 192to provide improved visibility of the surgical site during theprocedure. The view-port may be a window, a slot, or other structurethat allows increased visibility of the surgical site during theprocedure.

FIGS. 28a-28 e illustrate steps included in a spinal fusion procedureusing an embodiment of a holder 100. In FIG. 28a, holder 100 is shownbeing inserted into disk space 44 between adjacent vertebrae 54.Distractor 114 may be driven into the disk space 44 by strikinginsertion device 194 with mallet 196. Insertion device 194 may fit inthe conduits 104. Alternately, insertion device 194 may fit betweenconduits 104 in slot 118 to provide a contact surface with the holder100 for hammering. In the embodiments of the holder 100 shown in FIGS.20, 21, and 23, the insertion device may be an insertion tool 166 asshown in FIG. 22. The insertion device 194 may be coupled with holder100 prior to insertion into the surgical cavity, and may be used as ahandle for inserting and positioning holder 100 by the surgeon prior toand during hammering. Distractor 114 separates vertebrae 54 as thedistractor is hammered in. The distractor widens the disk space 44 tothe desired width for the procedure. Holder 100 may be hammered with themallet 196 until the bottom 146 of body 102 makes substantial contactwith the adjacent vertebra 54.

In FIG. 28b, holder 100 has been hammered into the disk space 44 to anoptimal depth. Optional flange 130 may then be slipped over the top ofholder 100 to fit snugly against flange rim 110. After flange 130 isinstalled, blood vessels 198, such as the aorta and vena cava, which areretracted to one side during the installation of the holder 100, may beplaced over flange 130 next to body 102, as shown in FIG. 29 and FIG.30. The shape of flange 130 serves to protect the blood vessels 198 frombeing pinched, nicked or cut during the remainder of the spinal fusionprocedure. Body 102 may be formed with smooth, arcuate outer surfaceswith no sharp corners to further protect blood vessels 198 and tissue.

FIG. 28c shows the insertion of optional fasteners 120 in fastener holes112, through end caps 122 and into cancellous bone 124 of vertebrae 54.Angling of fasteners 120 into cancellous bone 124 avoids verticalpenetration deep into the end plates 126; thus helping to preventweakening of the endplates near the implants 52. The head of driver 200may fit into slot 118 to contact a fastener 120. The slot 118 mayprotect surrounding soft tissues should the head of the driver 200 slipoff the fastener 120. Slot 118 may also help contain a fastener 120should the fastener be dropped during the insertion process. In someembodiments, the heads of fasteners 120 may include hex or star shapedslots for receiving a corresponding driver 200. In some embodiments,driver 200 may include a bent or bendable shaft to facilitate the angledinsertion of the fasteners 120 in the fastener holes 112. In someembodiments, the shaft of driver 200 may be long enough to allow thesurgeon to turn the driver above the surgical cavity while the head ofthe driver is coupled to the head of a fastener 120. In someembodiments, a fastener 120 may be coupled to the driving head of driver200 to help prevent dropping the fastener into the surgical cavityduring insertion.

In FIG. 28d, protective sleeve 132 is inserted in one of the conduits104 of the holder 100. Shaft 184 of driver 180 is inserted into theprotective sleeve 132. Stop 186 serves to limit the distance shaft 184may be inserted into sleeve 132. Drilling head 182 may be coupled to thedistal end of driver 180. A handle (not shown) coupled to the proximalend of driving shaft 184 may be turned while applying downward pressureon driver 180 to drill out a hole in disk space 44. Drilling the holemay also remove bone from the end plates 126 of adjacent vertebrae 54.Flange 130 may protect adjacent blood vessels 198 and other soft tissuesduring the drilling process.

In spinal fusion procedures using threaded implants, after the hole isdrilled, driver 180 is retracted and a tap (not shown) is attached tothe driver. The tap and the driver 180 are inserted into the sleeve 132.A handle (not shown) coupled to an end of the driving shaft 184 isturned while applying downward pressure on driver 180 to tap a flight ofthreads in the vertebrae 54. After a flight of threads is formed in thehole, the driver is removed from the protective sleeve 132.

Referring to FIG. 28e, a threaded implant 52 is coupled to the distalend of an implant insertion tool 202. The implant insertion tool 202 isinserted into the sleeve 132. A handle (not shown) coupled to theproximal end of implant insertion tool 132 is turned while applyingdownward pressure to screw implant 52 into the threaded hole in diskspace 44.

In spinal fusion procedures using unthreaded implants, after the hole isdrilled, an unthreaded implant 52 is coupled to an end of an implantinsertion tool 202. The implant insertion tool 202 is inserted into theprotective sleeve 132. A mallet (not shown) is used to strike theproximal end of implant insertion tool 202 to drive implant 52 into thedisk space 44.

In all embodiments, inserted implant 52 is then detached from insertiontool 202. Protective sleeve 132 may then be removed from the conduit 104of holder 100 and inserted into the adjacent holder conduit 104.Optionally, a second protective sleeve 132 may be inserted in theadjacent conduit 104. The steps described for FIGS. 28d-28 e may then berepeated for the installation of the second implant. After the secondimplant 52 is installed, fasteners 120 may be backed out of vertebrae 54and holder 100 may be removed from the disk space 44.

An advantage of holder 100 illustrated in FIGS. 28a-28 e is that thetools and protective sleeve 132 may be removed at any time during theprocedure without affecting the alignment or spacing of the holder 100.Fixing the holder 100 to the vertebrae with fasteners 120, and insertingthe protective sleeve 132 into the holder 100 only when necessary mayminimize the risk of misalignment of implants 52 during a spinal fusionprocedure.

FIG. 29 illustrates the positioning of major blood vessels 198 around adual-conduit holder 100 during an L5/S1fusion procedure. Holder 100 isshown inserted in disk space 44 (L5/S1) between vertebra 54 (L5) andsacrum 204 (S1). The bifurcation of major blood vessels 198 (the aortaand vena cava) typically is proximate vertebra L5. The right branch andleft branch of major blood vessels 198 are shown separated and placedover holder flange 130. In some patients, the bifurcation point of themajor blood vessels 198 may be located higher or lower than proximatethe L5 vertebra. An irregularly located bifurcation point of the majorblood vessels 198 may require the branches of the major blood vessels tobe routed around one side of holder 100.

FIG. 30 illustrates the positioning of major blood vessels 198 around aholder 100 during an L4/L5 fusion process. Holder 100 is shown insertedin disk space 44 (L4/L5) between adjacent vertebrae 54 (L4 and L5). Thebifurcation of major blood vessels 198 typically is proximate vertebraL5. The major blood vessels 198 are shown placed over holder 100 uponflange 130. The blood vessels may be placed on either side of holder100.

The configuration of holder 100 and the added protection of flexibleflange 130 may serve to protect the blood vessels 198 from being nickedduring the spinal fusion procedure. In addition, the body 102 of holder100 may be curved and may lack sharp corners or edges to further protectthe blood vessels 198 and other tissue from abrasion. Protecting theblood vessels 198 is critical in a spinal fusion procedure, as the aortais a major artery and the vena cava is a major vein. Even a tiny nick ineither blood vessel 198 is potentially catastrophic, and must berepaired quickly. A nick in the vena cava is particularly problematicbecause the vena cava has thinner walls than the aorta, making the venacava easier to nick and harder to repair than the aorta.

FIG. 3 illustrates the orientation of implants 52 inserted usingdual-tube protective sleeves 40 or an embodiment of holder 100 that hasan angle A value of 0 degrees. Implants 52 are shown inserted inparallel in disk space 44. Spinal nerves within the spinal canal 46 andprotective sheath 48 (also called the dura) are shown posterior to diskspace 44. Nerves 50 exit the sides of spinal canal 46. An end 206 of animplant 52 may put pressure on nerves 50 if the implant is inserted farenough to allow ends to protrude out the posterior side 138 of diskspace 44. Pressure on the nerves may lead to severe post-operative painor nerve damage for the patient.

FIG. 31 illustrates the angulation of implants inserted using oneembodiment of a holder 100. Implants 52 are shown inserted angledinwards in disk space 44. Nerves 50 are shown exiting from the sides ofspinal canal 46. If implants 52 are inserted far enough that ends 206protrude out the posterior side 138 of the disk space 44, ends 206 maybe more likely to put pressure on dura 48 than on nerves 50. Dura 48 maybe less likely to be negatively affected by the pressure than nerves 50.

Also shown in FIG. 31 is an embodiment of a holder 100 inserted in diskspace 44. The curvature of bottom 146 of holder 100 may substantiallymatch the curvature of the anterior surface of the adjacent vertebrae54. The close fit between the vertebrae 54 and the holder 100 may helpprotect blood vessels 198 and other soft tissues from being pinchedbetween the vertebrae and the holder during the spinal fusion procedure.The angulation of conduits 104 is shown as angle A. Differentembodiments of holder 100 may be made with a wide range of angles A tobe used in spinal fusion procedures requiring different optimalangulations of implants 52. Most procedures may fall between 0 degreesand 30 degrees. Approximately 8 degrees may be the optimal angulationfor implants 52 in many procedures.

Further modifications and alternative embodiments of various aspects ofthe invention will be apparent to those skilled in the art in view ofthis description. Accordingly, this description is to be construed asillustrative only and is for the purpose of teaching those skilled inthe art the general manner of carrying out the invention. It is to beunderstood that the forms of the invention shown and described hereinare to be taken as examples of embodiments. Elements and materials maybe substituted for those illustrated and described herein, parts andprocesses may be reversed, and certain features of the invention may beutilized independently, all as would be apparent to one skilled in theart after having the benefit of this description of the invention.Changes may be made in the elements described herein without departingfrom the spirit and scope of the invention as described in the followingclaims.

What is claimed is:
 1. A system for use during a spinal fusionprocedure, comprising: a holder, the holder comprising: a body; one ormore protrusions extending from the body, wherein a protrusion of theone or more protrusions is configured to couple the body in a disk spacebetween a first vertebra and a second vertebra, and wherein theprotrusion comprises serrations on at least one side of the protrusion;and a conduit through the body; a sleeve, wherein an end of the sleeveis removably positionable in the conduit; and wherein the sleeve isconfigured to allow tools or devices for implanting a spinal fusiondevice or for preparing a patient to receive a spinal fusion device tobe inserted in the disk space through the sleeve and through theconduit.
 2. The system of claim 1, wherein the at least one protrusionestablishes a separation distance between the first vertebra and thesecond vertebra during use.
 3. The system of claim 1, wherein a heightof the body is less than about two inches.
 4. The system of claim 1,wherein a height of the body is less than about four inches.
 5. Thesystem of claim 1, wherein the sleeve further comprises a view-port toprovide increased visibility of a surgical site during use.
 6. Thesystem of claim 1, further comprising an opening in the body, whereinthe opening is configured to accept a fastener that couples the body tothe first vertebra.
 7. The system of claim 1, further comprising asecond conduit through the body.
 8. The system of claim 1, furthercomprising a second conduit through the body, wherein a portion of theconduit overlaps a portion of the second conduit.
 9. A system for useduring a spinal fusion procedure, comprising: a holder, the holdercomprising: a body; one or more protrusions extending from the body,wherein a protrusion of the one or more protrusions is configured tocouple the body in a disk space between a first vertebra and a secondvertebra; and a conduit through the body; a sleeve, wherein an end ofthe sleeve is removably positionable in the conduit; wherein the sleeveis configure to allow tools or devices for implanting a spinal fusiondevice or for preparing a patient to receive a spinal fusion device tobe inserted in the disk space through the sleeve and through theconduit; and a flange configured to couple to the body to protect tissueand vessels adjacent to the disk space during use.
 10. The system ofclaim 9, wherein the sleeve comprises a view-port to provide increasedvisibility of a surgical site during use.
 11. The system of claim 9,wherein a height of the body is less than about four inches.
 12. Thesystem of claim 9, comprising a slot in a conduit wall, the slotconfigured to engage a distractor on an end of the sleeve during use.13. The system of claim 9, further comprising an opening in the body,wherein the opening is configured to accept a fastener that couples thebody to the first vertebra.
 14. The system of claim 9, furthercomprising a second conduit through the body.
 15. A system for useduring a spinal fusion procedure, comprising: a body having a height ofless than about 6 inches, the body comprising: a conduit through thebody; and one or more protrusions extending from the body, wherein aprotrusion of the one or more protrusions is configured to couple thebody to a first vertebra and a second vertebra, and wherein theprotrusion comprises serrations on at least one side of the protrusion;and wherein the conduit is configured to allow tools or devices forimplanting a spinal fusion device, or for preparing a patient to receivea spinal fusion device, to be inserted through the conduit into a diskspace between the first and the second vertebra.
 16. The system of claim15, further comprising a slot in a conduit wall, the slot configured toengage a distractor on an end of the at least one protrusion.
 17. Thesystem of claim 15, wherein the at least one protrusion establishes aseparation distance between the first vertebra and the second vertebraduring use.
 18. The system of claim 15, further comprising an opening inthe body, wherein the opening is configured to accept a fastener thatcouples the body to the first vertebra.
 19. The system of claim 15,further comprising a second conduit through the body.
 20. The system ofclaim 15, further comprising a second conduit through the body, whereina portion of the conduit overlaps a portion of the second conduit.
 21. Asystem for use during a spinal fusion procedure, comprising: a bodyhaving a height of less than about 6 inches, the body comprising: aconduit through the body; and one or more protrusions extending from thebody, wherein a protrusion of the one or more protrusions is configuredto couple the body to a first vertebra and a second vertebra; a flangepositionable around at least a portion of the body, wherein the flangeis configured to protect tissue and vessels adjacent to the disk spaceduring use; and wherein the conduit is configured to allow tools ordevices for implanting a spinal fusion device, or for preparing apatient to receive a spinal fusion device, to be inserted through theconduit into a disk space between the first vertebra and the secondvertebra.
 22. The system of claim 21, wherein a height of the body isless than about two inches.
 23. The system of claim 21, wherein at leastone protrusion of the one or more protrusions establishes a separationdistance between the first vertebra and the second vertebra during use.24. The system of claim 21, further comprising a slot in a conduit wall,the slot configured to engage a distractor an end of the sleeve duringuse.
 25. The system of claim 21, further comprising an opening in thebody, wherein the opening is configured to accept a fastener thatcouples the body to the first vertebra.
 26. The system of claim 21,further comprising a second conduit through the body.
 27. The system ofclaim 21, further comprising a second conduit through the body, whereina portion of the conduit overlaps a portion of the second conduit.
 28. Amethod for inserting an implant during a spinal fusion procedure,comprising: coupling at least one protrusion from a body of a holder toa first vertebra and a second vertebra; positioning a sleeve in aconduit of the holder; inserting tools or devices for implanting aspinal fusion device or for preparing a patient to receive a spinalfusion device through the sleeve and conduit into a disk space betweenthe first vertebra and the second vertebra; and protecting tissue andvessels adjacent to the disk space during use with a flange.
 29. Themethod of claim 28, further comprising limiting the insertion depth ofthe sleeve into the conduit with a shoulder located in the conduit. 30.The method of claim 28, further comprising engaging a distractor on anend of the sleeve during use with a slot in a wall of the conduit. 31.The method of claim 28, further comprising coupling the body to avertebra using a fastener positioned in an opening in the body.
 32. Themethod of claim 28, wherein the sleeve comprises a view-port to provideincreased visibility of a surgical site during use.
 33. The method ofclaim 28, wherein a height of the body is less than about six inches.34. The method of claim 28, wherein a height of the body is less thanabout two inches.